Explosive actuated tools (powder actuated tools) for driving pins and studs have been available for many years. One type of such tool has a rod, referred to as a piston, that slides up and down inside a barrel. On end of the barrel is referred to as the breach end and is fitted with a power load firing chamber and trigger mechanism. The other end is fitted with a lower end piece which receives and holds a pin or stud to be driven. A power load in the firing chamber is ignited to drive the piston down the barrel and against the pin head and into a work piece. Such a tool is more specifically described in U.S. Pat. No. 3,239,121, issued on Mar. 8, 1962, to Kopf et al.
A second type of tool is designed for achieving relatively higher driving capability, for example to drive 3/8" threaded studs or 3/8" headed pins into concrete and steel. In these tools, the pin is placed at the breach end of the barrel adjacent to the firing chamber and the ignition of the power load propels the pin down the barrel in free flight to impact the work piece as it emerges from the barrel end. A disclosure of this latter type of tool appears in U.S. Pat. No. 3,221,966, issued on Dec. 7, 1965, to Kopf et al.
The former tool is referred to as a low velocity piston tool (Lo V Tool) and the latter tool is referred to as a high velocity tool (Hi V Tool). The Lo V tool is considered much safter to operate because the pin or stud is never in free flight. However, it also typically generates a driving power that is far lower and has been used only for light and medium duty applications, e.g. fastening dry wall and window track to concrete or wood framing to concrete. Attempts to develop tools of the Lo V design with greater driving capability has, in the past, involved use of higher level power loads in order to drive the heavier piston. The firing chamber and thus the entire tool had to be massive in order to withstand the higher forces and recoil. The increased mass makes the tool unwieldy and undesirable for use as compared tot he Hi V tool even though safety is compromised.
It is an objective of the present invention to provide the Lo V piston tool, in its current light weight design, with the driving capability of the Hi V tool without sacrificing safety and other light-weight advantages.